Thermostatic bimetal strip



y 8,1969 c. c. PERRY 3,453,888 8 I THERMOSTATIC BIMEI'I'AL STRIP Filed May 31, 1966 CHARLES C. PERRY United States Patent 3,453,888 THERMOSTATIC BIMETAL STRIP Charles C. Perry, Ann Arbor, Mich., assiguor to W. M. Chace Company, Detroit, Mich., a corporation of Delaware Filed May 31, 1966, Ser. No. 553,827 Int. Cl. G01k /62 US. Cl. 73--363.5 2 Claims ABSTRACT OF THE DISCLOSURE A thermostatic bimetal in the form of an integral strip formed by first and second layers bonded together. The strip folded upon itself so that the order in which the layers are arranged on one end of the strip is reversed at the other end of the strip. The first layer is a high expansion component while the second layer is a low expansion component.

This invention relates generally to laminated elements in which the laminations are relatively reversed in different portions of the element, and more particularly to an improved one-piece reversed lamination element in which the element is folded upon itself.

This invention is particularly useful in connection with thermostatic bimetals, since there are numerous applications of this material which require a reversal of the high and low expanding sides of the bimetal within a particular element. For example, in a cantilever beam-type element, if the bimetal is reversed at the proper point along the length of the beam, the free end of the beam will not deflect vertically with temperature change, even though the relatively reversed portions of the beam exhibit changes in curvature. Such an arrangement has applications in a variety of ambient temperature compensating devices. Other applications of reversed bimetal include so-called linear motion actuators in which the bimetal element is initially formed of a somewhat sinuous shape. When this element is properly proportioned with respect to the point of reversal, the net effect of temperature change is to move one extremity of the element with respect to the other along a predetermined, substantially straight line. Still other applications of reversed thermostatic bimetal elements require two or more reversals of the high and low expanding sides of the bimetal in order to achieve certain specified modes of motion. The invention is also applicable to laminated materials other than thermostatic bimetal in which reversal is desired, and the detailed explanation which follows in connection with bimetal is for illustrative purposes only.

Reversed bimetal elements are commonly manufactured by either butt welding two segments, one of which has been inverted relative to the other, or by lap welding the segments. Both of these methods require welding and individual handling of the segments which are to be welded to make the reversed element. It is an object of this invention, therefore, to provide a laminated element in which the laminations are relatively reversed in different portions of the element which is formed by folding the portions of the element, thereby reducing the expense in manufacturing elements of this type and providing an improved one-piece element.

A further object of this invention is to provide a method of folding a laminated strip of material so as to relatively reverse the laminations in different portions of the strip which permits continuous production of reversed elements as the laminated material issues from the machine which forms the material, so that the strip can be folded mechanically and cutoff to form the desired individual elements.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims, and the accompanying drawing in which:

FIGURE 1 is a plan view of one form of the element of this invention;

FIGURE 2 is a plan view illustrating the first fold which is made in a strip being folded to form the element shown in FIG. 1;

FIGURE 3 is a plan view like FIG. 2 illustrating the second fold which is made in a strip to form the element shown in FIG. 1;

FIGURE 4 is an edge view of the element shown in FIG. 1, illustrating the element mounted as a cantilever beam and showing a deflected position of the beam in broken lines;

FIGURE 5 is a diagrammatic edge view of the element shown in FIG. 1, with the thickness of the element being exaggerated for illustrative purposes; and

FIGURES 6, 7 and 8 are views corresponding to FIGS. 1, 2 and 3 showing another form of the element of this invention and the folding steps which are followed to shape this form of the element of this invention.

With reference to the drawing, the reversed laminated element of this invention, indicated generally at 10, is illustrated in FIGS. 1 and 2 as consisting of an elongated strip 12 of laminated material having a surface lamination 14 on one side and a surface lamination 16 on the opposite side. It is to be understood that this invention is applicable to any laminated element in which it is desired to reverse the order of the laminations in a direction laterally of the element. As a result, the invention is applicable to thermostatic bimetal, trimetal, humidity responsive laminated material, and the like. Accordingly, in the following description only the surface laminations 14 and 16 are specifically referred to, although in a given embodiment of the invention more laminations may be present, and for purposes of illustration the surface lamination 14 is considered a high expanding metal, and the surface lamination 16 is considered a low expansion metal.

The element 10 is formed by first folding the strip 12 along a line 18 which, as shown in FIG 2, is inclined such that the end portions 20 and 22 of the strip 12 disposed on opposite sides of the line 18 are angularly arranged such that the included angle therebetween is approximately The portion 22 is then folded along a line 24 which is coincident with one edge 26 of the portion 20. The end portions 20 and 22 (FIG. 3) are now angularly arranged with an intermediate section 28 of generally triangular shape disposed therebetween. By virtue of the initial fold 18 being located such that the included angle between the portions 20 and 22 is 60, the section 28 is of equilateral triangle shape. The portion 22 is finally folded along a line 30 (FIG. 1) which is coincident with one edge 32 of the triangular section 28. The result of this fold line 30 is to form a second triangular section 34 which is superposed on the triangular section 28 with the sections 28 and 34 being of the same size and shape and being located in between the strip end portions 20 and 22 in a direction laterally of the element 10, as shown in FIG. 5. By proper folding, the fold lines can be made practically indistinguishable in the element 10, and when the element 10 is formed of a sufliciently thin material, the increased thickness portion formed by the four thicknesses of the strip at the area of connection of the end portions 20 and 22 can also be practically indistinguishable.

It is readily apparent that the element 10 can be formed directly at the outlet end of a rolling mill or other manufacturing or processing machine from which the laminated strip 12 issues continuously. All of the folding in the continuous strip issuing from the machine can be quickly accomplished mechanically and the continuous strip cut off to automatically form a plurality of elements As shown in FIG. 4, when an element 10, having the point of reversal located approximately one-quarter of the length away from one end, is fixed at that end 36 and heated uniformly, the opposite end 38 will not deflect vertically. FIG. 4 is included herein merely for the purpose of illustrating one common use for the element 10.

Another form of the reversed laminated element of this invention is illustrated in FIG. 6 and indicated generally by the numeral 105:. The element 10a is formed from a strip 40 having opposite side surface laminations 42 and 44 which are relatively reversed as illustrated in FIG. 6. This relative reversal is obtained by first folding the strip 40 along a fold line 46 so as to form end portions 48 and 50 of the strip 40 on opposite sides of the fold 46. The fold 46 is disposed at the same position as the fold 18 previously described so that the included angle between the portions 48 and 50 is about 60, as illustrated in FIG. 7.

The portion 50 is next olded along a fold line 52 (FIG. 8) disposed such that the end portions 48 and 50, following folding, are in an offset parallel relation. Folding along the line 52 accomplishes the formation of two triangular sections 54 and 56 which overlie the adjacent ends of the portions 48 and 50', respectively. As shown in FIG. 8, the triangular sections 54 and 56 are arranged so that they have a common base 58 which is coincident with the edges 60 and 62 of the portions 48 and 50, respectively.

It is apparent that at this stage of the folding of the strip 40, the surface laminations 42 and 44 are not relatively reversed, but that relative reversal and alignment of the end portions 48 and 50 can be accomplished by merely folding the strip along the base line 58. This folding can be in either direction and will still accomplish reversal. In the illustrated embodiment of the invention the end portion 50 is folded downwardly in the plane of the paper, as shown in FIG. 8, along the line 58, so as to position the end portions 48 and 50 in engagement with each other and with the triangular sections 54 and 56 on laterally opposite sides of the portions 48 and 50. The advantage of folding the strip 40" in this direction is that it avoids locating two thicknesses of the strip 40* between the aligned end portions 48 and 50. The element 10a can be automatically and continuously formed in the same manner as described above in connection with the element 10'.

From the above description it is seen that this invention provides one-piece laminated elements 10 and 10a in which the laminations in longitudinally spaced portions of the elements are relatively reversed. This is accomplished by folding of the strips 12 and 40 and does not require any cutting or welding of the strips. By virtue of the particular folding operations described above, a minimum of material is overlapped and the thickening of the elements at the folds is not sufiiciently great to affect the operability of the elements.

What is claimed is:

1. A thermostatic bimetal comprising a strip which is elongated and is constituted by first and second layers bonded together, the first layer defining one exposed surface of the strip and being a high expansion component, the second layer defining an opposite exposed surface of the strip and being a low expansion component, said strip being folded upon itself in a region intermediate its ends to define two sections extending substantially parallel in opposite directions from said region, said sections having a common longitudinal center line, the order of the two layers of one section being reversed as compared to the order of the two layers in the other section, said region and said sections being substantially coplanar.

2. A bimetal as set forth in claim 1 wherein said region includes a pair of superimposed substantially similar triangularly shaped portions of said strip.

References Cited UNITED STATES PATENTS 2,572,059 10/1951 Schlaich 73363.l X 3,238,779 3/1966 Wolfe 29-191 X ROBERT F. BURNETT, Primary Examiner.

RAYMOND O. LINKER, JR., Assistant Examiner.

US. Cl. X.R.

16l55, 102, 108; 29l9l.6, 195.5 

